Gravel Calculator
Work out how much gravel you need in cubic yards or cubic metres, with an optional weight estimate.
Your area
Filled in with example values. Replace them with your own.
Optional
Adds a percentage on top of the measured volume.
Needs the bulk density of your gravel. Ask your supplier: it varies by stone, size and moisture.
Results update as you type.
Result
Gravel needed: 1.11 yd³
You need about
1.11cubic yards
- Volume in cubic feet
- 30 ft³
- Volume in cubic metres
- 0.85 m³
- Area covered
- 120 ft²
- Estimated weight
- Turn on “Estimate weight”
How it’s calculated
Area
12 ft × 10 ft = 120 ft²
Volume
120 ft² × 0.25 ft deep = 30 ft³
In cubic yards
30 ft³ ÷ 27 = 1.11 yd³
How the gravel calculator works
Gravel is ordered by volume: cubic yards in the US, cubic metres in most other countries. To find the volume, the calculator treats your area as a rectangle filled to an even depth. It converts every measurement into the same unit, multiplies length by width to get the area, then multiplies the area by the depth.
If you turn on the allowance, it adds that percentage on top. If you enter a bulk density, it multiplies the final volume by the density to estimate the weight. Volume and weight are kept separate: the volume is measured from your area, while the weight is only as accurate as the density you enter.
The formula
Volume = Length × Width × Depth
Volume with extra = Volume × (1 + Extra % ÷ 100)
Weight = Volume with extra × Bulk density
All three measurements must be in the same unit before you multiply. Depth is the one people most often get wrong, because it is usually measured in inches or centimetres while the area is in feet or metres: 4 inches is 4 ÷ 12 = 0.333 feet, and 5 centimetres is 0.05 metres.
Worked example
A garden path is 20 feet long and 10 feet wide, and you want gravel 4 inches deep with 10% extra.
- Depth in feet: 4 ÷ 12 = 0.333 ft
- Area: 20 ft × 10 ft = 200 ft²
- Volume: 200 ft² × 0.333 ft = 66.67 ft³
- In cubic yards: 66.67 ÷ 27 = 2.47 yd³
- With 10% extra: 2.47 × 1.1 = 2.72 yd³ (73.33 ft³)
To estimate the weight, suppose your supplier quotes a bulk density of 100 lb/ft³. This figure is for illustration only; use your supplier’s. 73.33 ft³ × 100 lb/ft³ = 7,333 lb, and 7,333 ÷ 2,000 = about 3.67 US tons.
The same in metric: a path 5 m long, 2 m wide and 5 cm deep needs 5 × 2 × 0.05 = 0.5 m³ of gravel before any extra.
Units, assumptions and limitations
- Conversions use exact definitions: 1 inch = 2.54 cm, 1 foot = 12 inches, 1 yard = 3 feet, 1 lb = 0.45359237 kg.
- The area is treated as a flat rectangle with an even depth. Slopes, curves and dips change the real amount.
- The result is the volume of the space to fill. Loose gravel settles once it is spread and compacted, which is one reason to add extra.
- No density is assumed. A weight appears only when you supply one, and it is an estimate.
- Suppliers may sell by volume or by weight and may round to their own load sizes. Confirm the order with them.
Frequently asked questions
How many cubic feet are in a cubic yard?
Exactly 27. A cubic yard is a cube 3 feet on each side, and 3 × 3 × 3 = 27. That is why the calculator divides cubic feet by 27.
Why doesn’t the calculator show a weight straight away?
Weight depends on the bulk density of the gravel, and that varies with the type of stone, the size and mix of the pieces, how wet it is and how tightly it is packed. Any single built-in number would be wrong for many orders, so you enter the density yourself, ideally the figure your supplier uses.
How much extra gravel should I order?
There is no fixed rule. Extra covers uneven ground, spillage and settling as the gravel is walked or driven on. Many people add 5–10%; turn on “Add extra” to include it. For large or structural jobs, follow your contractor’s or supplier’s guidance.
How deep should the gravel be?
It depends on what the area is for and what is underneath. A decorative top layer on a path is usually a few inches, while driveways need thicker, layered construction on a prepared base. Check the recommendation for your project before ordering.
What if my area is not a rectangle?
Split it into rectangles, calculate each one, and add the volumes together. For a rough circle, an area of about 0.785 × diameter × diameter is a close starting point.
Is a ton the same as a tonne?
No. A US (short) ton is 2,000 lb, about 907 kg. A metric tonne is 1,000 kg, about 2,205 lb. The calculator shows US tons in imperial mode and tonnes in metric mode.